Storage subsystems, such as magnetic tape libraries, are widely used for storing information in digital form. These tape subsystems may include a storage subsystem controller for controlling one or more tape drives contained within the storage subsystem and for controlling other components of the storage subsystem, such as the tape picker, which is used to select and load tape cartridges into the tape drives. The storage subsystem may be coupled to a host system which transmits I/O requests to the storage subsystem via a host/storage connection.
The tape drive reads and writes data to the primary storage medium, which can be a magnetic tape medium contained within a removable magnetic tape cartridge. The magnetic tape medium typically comprises a thin film of magnetic material which stores the data. The tape medium may be moved by the tape drive between a pair of spaced apart reels and past a data transducer to record or read back information. In one type of tape drive system, one of the reels is part of the tape drive while the other reel is part of the removable tape cartridge. For this type of tape drive system, the reel which is a part of the tape drive is commonly referred to as a take-up reel, while the reel which is a part of the tape cartridge is commonly referred to as a cartridge reel.
Various methods have been used for loading a tape cartridge into a tape drive. In some manual loading systems, the tape cartridge is inserted into the tape drive by, for example, a robotic picker mechanism. The picker arm is typically configured to apply a force to the back of the tape cartridge to fully insert the tape cartridge into the tape drive. Upon insertion of the tape cartridge into the tape drive, a reel driver having a set of gears matching a set of gears provided on the bottom of the cartridge reel rises to couple with cartridge reel in the tape cartridge. A cartridge leader on the magnetic tape is coupled to the take-up reel of the tape drive. In this type of manual loading system, the tape cartridge travels in a single plane during the loading process. The picker mechanism provides an insertion force in a horizontal direction to drive the front of the cartridge to the location where the take-up leader coupling is to occur. Once the tape cartridge is firmly seated in the tape drive, the reel driver in the tape drive rises in the vertical direction (orthogonal to the horizontal insertion direction) to couple with the cartridge reel.
In other systems, sometimes referred to as “soft load” systems, the tape cartridge is placed in an initial loading location by the picker mechanism. The tape drive then assumes control of the tape cartridge and repositions the tape cartridge into the fully loaded location. This positioning typically requires that the tape cartridge first be translated in the horizontal direction and then be translated in the vertical direction until a stationary reel driver in the tape drive couples with the cartridge reel. Soft load systems can enable the tape drive to more accurately locate the tape cartridge in the final loaded positioning, free from the effects of a manual human load or library robotics variations. However, soft load mechanisms typically require complicated mechanical components for performing the various positioning tasks and two-dimensional movements of the tape cartridge. Such systems can be expensive to manufacture, complicated to operate, and prone to failure. It may be desirable, therefore, to provide a tape drive soft load mechanism that is cheaper, simpler, and more robust than existing soft load systems.